Process for producing a desulfurization sorbent

ABSTRACT

Particulate sorbent compositions which are suitable for the removal of sulfur from streams of cracked-gasoline or diesel fuel are provided which have increased porosity, improved resistance to deactivation through the addition of a calcium compound selected from the group consisting of calcium sulfate, calcium silicate, calcium phosphate or calcium aluminate to the support system comprised of zinc oxide, silica and alumina having thereon a promotor wherein the promotor is metal, metal oxide or metal oxide precursor with the metal being selected from the group consisting of cobalt, nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin and vanadium or mixtures thereof and wherein the valence of such promotor has been substantially reduced to 2 or less. Process for the preparation such sorbent systems as well as the use of same for the desulfurization of cracked-gasolines and diesel fuels are also provided.

FIELD OF THE INVENTION

This invention relates to the removal of sulfur from fluid streams ofcracked-gasolines and diesel fuels. In another aspect this inventionrelates to sorbent compositions suitable for use in the desulfurizationof fluid streams of cracked-gasolines and diesel fuel. A further aspectof this invention relates to a process for the production of sulfursorbents for use in the removal of sulfur bodies from fluid streams ofcracked gasolines and diesel fuels.

BACKGROUND OF THE INVENTION

The need for cleaner burning fuels has resulted in a continuing worldwide effort to reduce sulfur levels in gasoline and diesel fuels. Thereducing of gasoline and diesel sulfur is considered to be a means forimproving air quality because of the negative impact the fuel sulfur hason the performance of automotive catalytic converters. The presence ofoxides of sulfur in automotive engine exhaust inhibits and mayirreversibly poison noble metal catalysts in the converter. Emissionsfrom an inefficient or poisoned converter contain levels ofnon-combusted, non-methane hydrocarbon and oxides of nitrogen and carbonmonoxide. Such emissions are catalyzed by sunlight to form ground levelozone, more commonly referred to as smog.

Most of the sulfur in gasoline comes from the thermally processedgasolines. Thermally processed gasolines such, as for example, thermallycracked gasoline, visbreaker gasoline, coker gasoline and catalyticallycracked gasoline (hereinafter collectively called “cracked-gasoline”)contains in part olefins, aromatics, and sulfur-containing compounds.

Since most gasolines, such as for example automobile gasolines, racinggasolines, aviation gasoline and boat gasolines contain a blend of atleast in part cracked-gasoline, reduction of sulfuir in cracked-gasolinewill inherently serve to reduce the sulfur levels in such gasolines.

The public discussion about gasoline sulfur has not centered on whetheror not sulfur levels should be reduced. A consensus has emerged thatlower sulfur gasoline reduces automotive emissions and improves airquality. Thus the real debate has focused on the required level ofreduction, the geographical areas in need of lower sulfur gasoline andthe time frame for implementation.

As the concern over the impact of automotive air pollution continues, itis clear that further efforts to reduce the sulfur levels in automotivefuels will be required. While the current gasoline products containabout 330 part per million with continued efforts by the EnvironmentalProtection Agency to secure reduced levels, it has been estimated thatgasoline will have to have less than 50 part per million of sulfur bythe year 2010. (See Rock, K. L., Putman H. M., Improvements in FCCGasoline Desulfurization via Catalytic Distillation” presented at the1998 National Petroleum Refiners Association Annual Meeting (AM-98-37)).

In view of the ever increasing need to be able to produce a low sulfurcontent automotive fuel, a variety of processes have been proposed forachieving industry compliance with the Federal mandates.

One such process which has been proposed for the removal of sulfur fromgasoline is called hydrodesulfurization. While hydrodesulfurization ofgasoline can remove sulfur-containing compounds, it can result in thesaturation of most, if not all, of the olefins contained in thegasoline. This saturation of olefins greatly affects the octane number(both the research and motor octane number) by lowering it. Theseolefins are saturated due to, in part, the hydrodesulfmrizationconditions required to remove thiophenic compounds (such as, forexample, thiophene, benzothiophene, alkyl thiophenes,alkylbenzothiphenes and alkyl dibenzothiophenes), which are some of themost difficult sulfur-containing compounds to removed. Additionally, thehydrodesulfurization conditions required to remove thiophenic compoundscan also saturate aromatics.

In addition to the need for removal of sulfur from cracked-gasolines,there is also presented to the petroleum industry a need to reduce thesulfur content of diesel fuels. In removing sulfur from diesel byhydrodesuifirization, the cetane is improved but there is a large costin hydrogen consumption. This hydrogen is consumed by bothhydrodesulfurization and aromatic hydrogenation reactions.

Thus there is a need for a process wherein desulfurization withouthydrogenation of aromatics is achieved so as to provide a moreeconomical process for the treatment of diesel fuels.

As a result of the lack of success in providing successful andeconomically feasible process for the reduction of sulfur levels in bothcracked-gasolines and diesel fuels, it is apparent that there is stillneeded a better process for the desulfurization of bothcracked-gasolines and diesel fuels which has minimal affect of octanewhile achieving high levels of sulfur removal.

While it has been shown in my copending application Desulfurization andNovel Sorbents for Same, Ser. No.382,935 filed Aug. 25, 1999, that onesuitable sorbent system for the desulfurization of cracked-gasolines ordiesel fuels is that employing a cobalt metal on a zinc oxide, silica,alumina support, there is a continuous effort to develop additionalsystems which permits the effecting of the desired desulfurization ofsuch cracked-gasolines or diesel fuels and which also provide foralternative desulfurization conditions to permit variations within theoperation parameters.

It is thus an object of the present invention to provide a novel sorbentsystem for the removal of sulfur from fluid streams of cracked-gasolinesand diesel fuels.

Another object of this invention is to provide a process for theproduction of novel sorbents which are useful in the desulfurization ofsuch fluid streams.

Another object of this invention is to provide a process for the removalof sulfur-containing compounds from cracked-gasolines and diesel fuelswhich minimize saturation of olefins and aromatics therein.

A still further object of this invention is to provide a desulfurizedcracked-gasoline that contains less than about 100 parts per million ofsulfur based on the weight of the desulfurized cracked-gasoline andwhich contains essentially the same amount of olefins and aromatics aswere in the cracked-gasoline from which it is made.

Other aspects, objects and the several advantages of this invention willbe apparent from the following description of the invention and theappended claims.

SUMMARY OF THE INVENTION

The present invention is based upon my discovery that through theutilization of a promotor derived from a metal, metal oxide or metaloxide precursor wherein the metal is selected from the group consistingof cobalt, nickel, iron, manganese, copper, molybdenum, tungsten,silver, tin and vanadium and mixtures thereof and wherein such metal isin a substantially reduced valence state, two or less, and wherein suchmetal is on a support comprising zinc oxide, silica, alumina and acalcium compound selected from the group consisting of calcium sulfate,calcium aluminate, calcium phosphate and calcium silicate there isachieved a novel sorbent composition which permits the ready removal ofsulfur from streams of cracked-gasoline or diesel fuels with a minimaleffect on the octane rating of the treated stream.

Such a sorbent system is further based upon my discovery that the use ofa calcium compound selected from the group consisting of calciumsulfate, calcium aluminate and calcium silicate provides better porosityto the promotor support and serves to improve the attrition resistanceof the support composition.

In addition, I have further discovered that through the replacement of aportion of the silica content of a support composition comprising zincoxide, silica and alumina with a calcium compounds selected from thegroup consisting of calcium sulfate, calcium aluminate, calciumphosphate and calcium silica there is obtained a sorbent system havingextended life through a reduction in the deactivation rate of thesorbent composition.

Accordingly, in one aspect of the present invention there is provided anovel sorbent suitable for the desulftirization of cracked-gasolines ordiesel fuels which is comprised of zinc oxide, silica, alumina and acalcium compound selected from the group consisting of calcium sulfate,calcium aluminate, calcium phosphate and calcium silicate and a promotormetal, metal oxide or metal oxide precursor wherein the metal isselected from the group consisting of cobalt, nickel, iron, manganese,copper, molybdenum, tungsten, silver, tin and vanadium or mixturesthereof wherein the valence of the promotor metal is substantiallyreduced and wherein such reduced valence promotor is present in anamount to permit the removal of sulfur from cracked-gasolines or dieselfuels.

In accordance with another aspect of the present invention, there isprovided a process for the preparation of a novel sorbent compositionwhich comprises admixing zinc, oxide, silica, alumina and a calciumcompound selected from the group consisting of calcium sulfate, calciumaluminate, calcium phosphate and calcium silicate so as to form a wetmix, dough, paste or slurry thereof, particulating the wet mix, dough,paste or slurry thereof so as to form as particulate granule, extrudate,tablet, sphere, pellet or microsphere thereof, drying the resultingparticulate; calcining the dried particulate; impregnating the resultingsolid particulate with a metal, metal oxide or metal oxide precursorwherein the metal is selected from the group consisting of cobalt,nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin andvanadium or mixtures thereof; drying the resulting impregnated solidparticulate composition; calcining the dried particulate composition;and reducing the calcined product with a suitable reducing agent, suchas hydrogen, so as to produce a sorbent composition having a reducedpromotor metal content in an amount which is sufficient to permit theremoval with same of sulfur from a cracked-gasoline or diesel fuelstream.

In accordance with a further aspect of the present invention there isprovided a process for the desulfurization of a cracked-gasoline ordiesel fuel stream which comprises desulfurizing in a desulfurizationzone cracked-gasoline or diesel fuel with a sorbent compositioncomprising a promotor metal on a support composition comprised of zincoxide, silica, alumina and a calcium compound selected from the groupconsisting of calcium sulfate, calcium aluminate, calcium phosphate andcalcium silicate wherein said promotor metal is present in asubstantially reduced valence and in an amount which effects the removalof sulfur from a stream of cracked-gasoline or diesel fuel whencontacted with same under desulfurization conditions; separating thedesulfurized cracked-gasoline or diesel fuel from the sulfurizedsorbent, regenerating at least a portion of the sulfurized sorbent toproduce a regenerated desulfurized solid sorbent; activating at least aportion of the regenerated desulfurized sorbent to produce a solidsorbent having a reduced metal content; and thereafter returning atleast a portion of the resulting reduced promotor metal containingsorbent to the desulfurization zone.

The novel sorbents of the present invention are useful for the removalof thiophenic sulfur compounds from fluid streams of cracked-gasoline ordiesel fuel without having a significant adverse affect on the olefincontent of such streams, thus avoiding a significant reduction of octanevalues of the treated stream. Moreover, the use of such novel sorbentsresults in a significant reduction of the sulfur content of theresulting treated fluid stream.

DETAILED DESCRIPTION OF THE INVENTION

The term “gasoline” as employed herein is intended to mean a mixture ofhydrocarbons boiling from about 100° F. to approximately 400° F. or anyfraction thereof. Such hydrocarbons will include, for example,hydrocarbon streams in refineries such as naphtha, straight-run naphtha,coker naphtha, catalytic gasoline, visbreaker naphtha, alkylate,isomerate or reformate.

The term “cracked-gasoline” as employed herein is intended to meanhydrocarbons boiling from about 100° F. to approximately 400° F. or anyfraction thereof that are products from either thermal or catalyticprocesses that crack larger hydrocarbon molecules into smallermolecules. Examples of thermal processes include coking, thermalcracking and visbreaking. Fluid catalytic cracking and heavy oilcracking are examples of catalytic cracking. In some instances thecracked-gasoline may be fractionated and/or hydrotreated prior todesulfurization when used as a feed in the practice of this invention.

The term “diesel fuel” as employed herein is intended to mean a fluidcomposed of a mixture of hydrocarbons boiling from about 300° F. toapproximately 750° F. or any fraction thereof. Such hydrocarbon streamsinclude light cycle oil, kerosene, jet fuel, straight-run diesel andhydrotreated diesel.

The term “sulfur” as employed herein is intended to mean thoseorganosulfur compounds such as mercaptans or those thiophenic compoundsnormally present in cracked gasolines which include among othersthiophene, benzothiophene, alkyl thiophenes, alkyl benzothiophenes andalkyldibenzothiophenes as well as the heavier molecular weights of samewhich are normally present in a diesel fuel of the types contemplatedfor processing in accordance with the present invention.

The term “gaseous” as employed herein is intended to mean that state inwhich the feed cracked-gasoline or diesel fuel is primarily in a vaporphase.

The term “substantially reduced valence” as employed herein is intendedto mean that a large portion of the valence of the promotor metalcomponent of the sorbent composition is reduced to a lower valencestate, preferably zero.

The term “promotor” or “promotor metal” as employed herein is intendedto mean a metal, metal oxide or metal oxide precursor wherein the metalis selected from the group consisting of cobalt, nickel, iron,manganese, copper, molybdenum, tungsten, silver, tin and vanadium, ormixtures thereof.

The present invention is based upon applicant's discovery that throughthe use of a promotor or promotor metal as above defined wherein thevalence of such promotor has been substantially reduced and wherein suchreduce valence promotor is on a support comprising zinc oxide, silica,alumina and a calcium compound selected from the group consisting ofcalcium sulfate, calcium aluminate, calcium phosphate and calciumsilicate there is achieved a novel sorbent composition which permits theready removal of sulfur from streams of cracked-gasoline or diesel fuelswith a minimal effect on the octane rating of the treated stream.

In a presently preferred embodiment of this invention, the sorbentcomposition has a promotor content in the range of from about 5 to about50 weight percent weight of sorbent composition.

The zinc oxide used in the preparation of the sorbent composition caneither be in the form of zinc oxide, or in the form of one or more zinccompounds that are convertible to zinc oxide under the conditions ofpreparation described herein. Examples of such zinc compounds include,but are not limited to, zinc sulfide, zinc sulfate, zinc hydroxide, zinccarbonate, zinc acetate, and zinc nitrate. Preferably, the zinc oxide isin the form of powdered zinc oxide.

The silica used in the preparation of the sorbent compositions may beeither in the form of silica or in the form of one or moresilicon-containing compounds. Any suitable type of silica may beemployed in the sorbent compositions of the present invention. Examplesof suitable types of silica include diatomite, silicalite, silicacolloid, flame-hydrolyzed silica, hydrolyzed silica, silica gel andprecipitated silica, with diatomite being presently preferred. Inaddition, silicon compounds that are convertible to silica such assilicic acid, sodium silicate and ammonium silicate can also beemployed. Preferably, the silica is in the form of diatomite.

The starting alumina component of the composition can be any suitablecommercially available alumina material including colloidal aluminasolutions and, generally, those alumina compounds produced by thedehydration of alumina hydrates.

The calcium component of the sorbent composition is one selected fromthe group consisting of calcium sulfate, calcium silicate, calciumphosphate and calcium aluminate.

In achieving the advantages of the sorbent system of the presentinvention, the sorbent support should contain a calcium compound in anamount in the range of about 5 to about 90 weight percent of the amountof silica present in the sorbent composition. In one presently preferredembodiment of the invention the calcium compound is present in an amountsuch that the ratio of calcium to silica is in the range of about 0.1 toabout 0.9.

In formulating the novel sorbent system of the present invention, thezinc oxide will generally be present in the sorbent composition in anamount in the range of about 10 weight percent to about 90 weightpercent and preferably in an amount in the range of from about 15 toabout 60 weight percent when such weight percents are expressed in termsof the zinc oxide based upon the total weight of the sorbentcomposition.

The silica will generally be present in the sorbent composition in anamount in the range of from about 5 weight percent to about 85 weightpercent, preferably in an amount in the range of from about 20 weightpercent to about 60 weight percent when the weight percents areexpressed in terms of the silica based upon the total weight of thesorbent composition.

The alumina will generally be present in the sorbent composition in anamount in the range of from about 5 weight percent to about 30 weightpercent, preferably from about 5 weight percent to about 15 weightpercent when such weight percents are expressed in terms of the weightof the alumina compared with the total weight of the sorbent system.

In the manufacture of the sorbent composition, the primary components ofzinc oxide, silica, alumina and calcium are combined together inappropriate proportions by any suitable manner which provides for theintimate mixing of the components to provide a substantially homogeneousmixture.

Any suitable means for mixing the sorbent components can be used toachieve the desired dispersion of the materials. Such means include,among others, tumblers, stationary shells or troughs, Muller mixers,which are of the batch or continuous type, impact mixers and the like.It is presently preferred to use a Muller mixer in the mixing of thesilica, alumina, zinc oxide and calcium components.

Once the sorbent components are properly mixed to provide a shapeablemixture, the resulting mixture can be in the form of wet mix, dough,paste or slurry. If the resulting mix is in the form of a wet mix, thewet mix can be densified and thereafter particulated through thegranulation of the densified mix following the drying and calcination ofsame. When the admixture of zinc oxide, silica, alumina and calciumresults in a form of the mixture which is either in a dough state orpaste state, the mix can be shaped to form a particulate granule,extrudate, tablet, sphere, pellet or microsphere. Presently preferredare cylindrical extrudates having from {fraction (1/32)} inch to ½ inchdiameter and any suitable length. The resulting particulate is thendried and then calcined. When the mix is in the form of a slurry, theparticulation of same is achieved by spray drying the slurry to formmicrospheres thereof having a size of from about 20 to about 500microns. Such microspheres are then subjected to drying and calcination.Following the drying and calcination of the particulated mixture, theresulting particulates can be impregnated with a promotor derived from ametal, metal oxide or metal oxide precursor wherein the metal isselected from the group consisting of cobalt, nickel, iron, manganese,copper, molybdenum, tungsten, silver, tin and vanadium or mixturesthereof.

Following the impregnation of the particulate compositions with theappropriate promotor metal compound, the resulting impregnatedparticulate is then subjected to drying and calcination prior to thesubjecting of the calcined particulate to reduction with a reducingagent, preferably hydrogen.

The promotor metal can be added to the particulated support material byimpregnation of the mixture with a solution, either aqueous or organic,that contains the selected promotor compound. In general, theimpregnation with the promotor is carried out so as to form a resultingparticulate composition of support and promotor prior to the drying andcalcination of the resulting impregnated sorbent composition.

The impregnation solution is any aqueous solution or organic solutionand amounts of such solution which suitably provides for theimpregnation of the support mixture to give an amount of promotor metalin the final support-promotor composition to provide when reduced, areduced valence promotor metal content sufficient to permit the removalof sulfur from streams of cracked-gasoline or diesel fuels when sotreated with same in accordance with the process of the presentinvention.

Once the promotor has been incorporated into the particulated supportmixture, the desired reduced valence promotor metal containing sorbentis prepared by drying the resulting composition followed by calcinationand thereafter subjecting the resulting calcined composition toreduction with a suitable reducing agent, preferably hydrogen, so as toproduce a sorbent composition having a substantial reduced valencepromotor metal, preferably having a zero valence content, with suchreduced metal content being present in an amount to permit the removalwith same of sulfur from a cracked-gasoline or diesel fuel fluid stream.

The solid reduced metal sorbent of this invention are compositions thathas the ability to react with and/or chemisorb with organosulfurcompounds, such as thiophenic compounds. In addition such sorbents serveto remove diolefins and other gum forming compounds from thecracked-gasoline.

The solid reduced metal sorbent of this invention is comprised of apromotor or promotor metal that is in a substantially reduced valencestate, preferably two or less. The amount of reduced promotor metal inthe novel sorbents of this invention is that amount which will permitthe removal of sulfur from a cracked-gasoline or diesel fuel fluidstream. Such amounts are generally in the range of from about 5 to about50 weight percent of the total weight of the promotor metal in thesorbent composition. Presently, it is preferred that the reduced valencepromotor metal be present in an amount in the range of from about 15 toabout 40 weight percent of the total weight of promotor metal in thesorbent composition.

In one presently preferred embodiment of the present invention, zincoxide is present in an amount of about 39 weight percent, silica ispresent in an amount of about 23 weight percent, alumina is present inan amount of about 8 weight percent, the calcium component is calciumsulfate and is present in an amount of about 8 weight percent and thepromotor is nickel and is present in an amount of about 23 weightpercent prior to reduction substantially to zero valence.

From the above, it can be appreciated that the sorbent compositionswhich are useful in the desulfurization process of this invention can beprepared by a process which comprises:

(a) admixing zinc oxide, silica, alumina and calcium component so as toform a mix of same in the form of one of a wet mix, dough, paste orslurry;

(b) particulating the resulting mix to form particulates thereof in theform of one of granules, extrudates, tablets, pellets, spheres ormicrospheres;

(c) drying the resulting particulate;

(d) calcining the dried particulate;

(e) impregnating the resulting calcined particulate with a metal, metaloxide or metal oxide precursor promotor having as a metal componenttherein at least one metal selected from the group consisting cobalt,nickel, iron, manganese, copper, molybdenum, tungsten, silver, tin andvanadium;

(f) drying the impregnated particulate;

(g) calcining the resulting dried particulate; and

(h) reducing the calcined particulate product of (g) with a suitablereducing agent so as to produce a particulate composition having asubstantial reduced valence promotor metal content therein and whereinthe reduced valence promotor metal content is present in an amountsufficient to permit the removal with same of sulfur from acracked-gasoline or diesel fuel fluid stream when contacted with theresulting substantially reduced valence promotor particulated sorbent.

The process to use the novel sorbents to desulfurize cracked-gasoline ordiesel fuels to provide a desulftirized cracked-gasoline or diesel fuelcomprises:

(a) desulfurizing in a desulfurization zone a cracked-gasoline or dieselfuel with a solid reduced promotor metal containing sorbent;

(b) separating the desulfurized cracked-gasoline or desulfurized dieselfuel from the resulting sulfurized solid reduced promotor metalcontaining sorbent;

(c) regenerating at least a portion of the sulfurized solid reducedmetal containing sorbent to produce a regenerated desulfurized solidmetal containing sorbent;

(d) reducing at least a portion of the regenerated desulfurized solidmetal containing sorbent to produce a solid reduced metal containingsorbent, and thereafter;

(e) returning at least a portion of the regenerated solid reduced metalcontaining sorbent to the desulfurization zone.

The desulfurization step (a) of the present invention is carried outunder a set of conditions that includes total pressure, temperature,weight hourly space velocity and hydrogen flow. These conditions aresuch that the solid reduced promotor containing sorbent can desulfurizethe cracked-gasoline or diesel fuel to produce a desulfurizedcracked-gasoline or desulfurized diesel fuel and a sulfurized sorbent.

In carrying out the desulfurization step of the process of the presentinvention, it is preferred that the feed cracked-gasoline or diesel fuelbe in a vapor phase. However, in the practice of the invention it is notessential, albeit preferred, that the feed be totally in a vapor orgaseous state.

The total pressure can be in the range of about 15 psia to about 1500psia. However, it is presently preferred that the total pressure be in arange of from about 50 psia to about 500 psia.

In general, the temperature should be sufficient to keep thecracked-gasoline or diesel fuel essentially in a vapor phase. While suchtemperatures can be in the range of from about 100° F. to about 1000°F., it is presently preferred that the temperature be in the range offrom about 400° F. to about 800° F. when treating as cracked-gasolineand in the range of from about 500° F. to about 900° F. when the feed isa diesel fuel.

Weight hourly space velocity (WHSV) is defined as the pounds ofhydrocarbon feed per pound of sorbent in the desulfurization zone perhour. In the practice of the present invention, such WHSV should be inthe range of from about 0.5 to about 50, preferably about 1 to about 20hr⁻¹.

In carrying out the desulfurization step, it is presently preferred thatan agent be employed which interferes with any possible chemisorbing orreacting of the olefinic and aromatic compounds in the fluids which arebeing treated with the solid reduced promotor metal containing sorbent.Such an agent is presently preferred to be hydrogen.

Hydrogen flow in the desulfurization zone is generally such that themole ratio of hydrogen to hydrocarbon feed is the range of about 0.1 toabout 10, and preferably in the range of about 0.2 to about 3.0.

The desulfurization zone can be any zone wherein desulfurization of thefeed cracked-gasoline or diesel fuel can take place. Examples ofsuitable zones are fixed bed reactors, moving bed reactors, fluidizedbed reactors and transport reactors. Presently, a fluidized bed reactoror a fixed bed reactor is preferred.

If desired, during the desulfurization of the vaporized fluids, diluentssuch as methane, carbon dioxide, flue gas, and nitrogen can be used.Thus it is not essential to the practice of the process of the presentinvention that a high purity hydrogen be employed in achieving thedesired desulfurization of the cracked-gasoline or diesel fuel.

It is presently preferred when utilizing a fluidized system that a solidreduced promotor metal sorbent be used that has a particle size in therange of about 20 to about 1000 micrometers. Preferably, such sorbentsshould have a particle size of from about 40 to about 500 micrometers.When a fixed bed system is employed for the practice of thedesulfurization process of this invention, the sorbent should be such asto have a particle size in the range of about {fraction (1/32)} inch toabout ½ inch diameter.

It is further presently preferred to use solid reduced promotor metalsorbents that have a surface area of from about 1 square meter per gramto about 1000 square meters per gram of solid sorbent.

The separation of the gaseous or vaporized desulfurized fluids andsulfurized sorbent can be accomplished by any means known in the artthat can separate a solid from a gas. Examples of such means arecyclonic devices, settling chambers or other impingement devices forseparating solids and gases. The desulfurized gaseous cracked-gasolineor desulfurized diesel fuel can then be recovered and preferablyliquefied.

The gaseous cracked-gasoline or gaseous diesel fuel is a compositionthat contains in part, olefins, aromatics and sulfur-containingcompounds as well as paraffins and naphthenes.

The amount of olefins in gaseous cracked-gasoline is generally in therange of from about 10 to 35 weight percent based on the weight of thegaseous cracked-gasoline. For diesel fuiel there is essentially noolefin content.

The amount of aromatics in gaseous cracked-gasoline is generally in therange of about 20 to about 40 weight percent based on the weight of thegaseous cracked gasoline. The amount of aromatics in gaseous diesel fuelis generally in the range of about 10 to about 90 weight percent.

The amount of sulfuir in cracked-gasolines or diesel fuels can rangefrom about 100 parts per million sulfur by weight of the gaseouscracked-gasoline to about 10,000 parts per million sulfuir by weight ofthe gaseous cracked-gasoline and from about 100 parts per million toabout 50,000 parts per million for diesel fuel prior to the treatment ofsuch fluids with the sorbent system of the present invention.

The amount of sulfur in cracked-gasolines or in diesel fuels followingtreatment of same in accordance with the desulfurization process of thisinvention is less than 100 parts per million.

In carrying out the process of this invention, if desired, a stripperunit can be inserted before the regenerator for regeneration of thesulfuirized sorbent which will serve to remove a portion, preferablyall, of any hydrocarbons from the sulfuirized sorbent or before thehydrogen reduction zone so as to remove oxygen and sulfur dioxide fromthe system prior to introduction of the regenerated sorbent into thesorbent activation zone. The stripping comprises a set of conditionsthat includes total pressure, temperature and stripping agent partialpressure.

Preferably the total pressure in a stripper, when employed, is in arange of from about 25 psia to about 500 psia.

The temperature for such strippers can be in the range of from about100° F. to about 1000° F.

The stripping agent is a composition that helps to remove hydrocarbonsfrom the sulfurized solid sorbent. Presently, the preferred strippingagent is nitrogen.

The sorbent regeneration zone employs a set of conditions such that atleast a portion of the sulfurized sorbent is desulfurized.

The total pressure in the regeneration zone is generally in the range offrom about 10 to about 1500 psia. Presently preferred is a totalpressure in the range of from about 25 psia to about 500 psia.

The sulfur removing agent partial pressure is generally in the range offrom about 1 percent to about 25 percent of the total pressure.

The sulfur removing agent is a composition that helps to generategaseous sulfur oxygen-containing compounds such as sulfur dioxide, aswell as to burn off any remaining hydrocarbon deposits that might bepresent. Currently, oxygen-containing gases such as air are thepreferred sulfur removing agents.

The temperature in the regeneration zone is generally from about 100° F.to about 1500° F. with a temperature in the range of about 800° F. toabout 1200° F. being presently preferred.

The regeneration zone can be any vessel wherein the desulfurizing orregeneration of the sulfurized sorbent can take place.

The desulfurized sorbent is then reduced in an activation zone with areducing agent so that at least a portion of the promotor metal contentof the sorbent composition is reduced to produce a solid reduced metalsorbent having an amount of reduced metal therein to permit the removalof sulfur components from a stream of cracked-gasoline or diesel fuel.

In general, when practicing the process of this invention, the reductionof the desulfurized solid promotor containing sorbent is carried out ata temperature in the range of about 100° F. to about 1500° F. and apressure in the range of about 15 to 1500 psia. Such reduction iscarried out for a time sufficient to achieve the desired level ofpromotor reduction in the sorbent system. Such reduction can generallybe achieved in a period of from about 0.01 to about 20 hours.

Following the activation of the regenerated particulate sorbent, atleast a portion of the resulting activated (reduced) sorbent can bereturned to the desulfurization unit.

When carrying out the process of the present invention in a fixed bedsystem, the steps of desulfurization, regeneration, stripping, andactivation are accomplished in a single zone or vessel.

The desulfurized cracked-gasoline resulting from the practice of thepresent invention can be used in the formulation of gasoline blends toprovide gasoline products suitable for commercial consumption.

The desulfurized diesel fuels resulting from the practice of the presentinvention can likewise be used for commercial consumption where a lowsulfur-containing fuel is desired.

EXAMPLES

The following examples are intended to be illustrative of the presentinvention and to teach one of ordinary skill in the art to make and usethe invention. These examples are not intended to limit the invention inany way.

Example I

A solid reduced nickel metal sorbent was produced by dry mixing 568grams of diatomite silica and 945 grams of zinc oxide and 189 gramsCaSO₄ in a mix-Muller for 10 minutes to produce a first mixture. Whilestill mixing, a solution containing 241 grams of Disperal alumina(Condea), 850 grams of deionized water and 26 grams of glacial aceticacid, were added to the mix-Muller to produce a second mixture. Afteradding these components, mixing continued for an additional 25 minutes.This second mixture was then dried at 300° F. for 3 hours and thencalcined at 1175° F. for 1 hour to form a third mixture. This thirdmixture was then particulated by granulation using a Stokes PennwaltGranulator fitted with a 50 mesh screen. Fifty grams of resultinggranulated mixture was impregnated with 37.1 grams of nickel nitratehexahydrate dissolved in 11.7 grams of hot deionized water to produce afirst impregnated particulate. The first impregnated particulate wasdried at 300° F. for one hour and then calcined at 1175° F. for one hourto form a solid particulate nickel oxide-containing composition. Theresulting calcined particulate was impregnated with 37.1 g Ni (NO₃)₂.6H₂O dissolved in 9.0 g deionized water. The second impregnatedparticulate was again dried at 300° F. for one hour and then calcined at1175° F. for one hour.

Reduction of the particulate solid calcined composition comprising zincoxide, silica, alumina, calcium sulfate and a nickel compound so as toobtain the desired sorbent having a reduced valence nickel content iscarried out in the reactor as described in Example II. Alternatively,such reduction or activation of the particulate composition to form thedesired sorbent can be carried out in a separate activation orhydrogenation zone and subsequently transferred to the unit in whichdesulfurization of the feedstock is to be carried out.

Example II

The particulate solid nickel sorbent as prepared in Example I was testedfor its desulfurization ability as follows.

A 1-inch quartz reactor tube was loaded with the indicated amounts asnoted below of the sorbent of Example I. This solid nickel sorbent wasplaced on a frit in the middle of the reactor and subjected to reductionwith hydrogen at a total pressure of 15 psia and hydrogen partialpressure of 15 psi for 0.03 hr. Gaseous cracked-gasoline having about340 parts per million sulfur by weight sulfuir-containing compoundsbased on the weight of the gaseous cracked-gasoline and having about 95weight percent thiophenic compounds (such as for example, alkylbenzothiophenes, alkyl thiophenes, benzothiophene and thiophene) basedon the weight of sulfur-containing compounds in the gaseouscracked-gasoline was then pumped upwardly through the reactor. The ratewas 13.4 milliliters per hour. This produced sulfurized solid sorbentand desulfurized gaseous-cracked gasoline. In Run 1, hydrogen was addedto the cracked-gasoline feed at a partial pressure of 13.2 psi whichresulted in the reduction of sulfur content of gasoline from 340 ppm toless than or equal to 5 ppm.

After Run 1, the sulfurized sorbent was subjected to desulfurizingconditions that included a temperature of 900° F., a total pressure of15 psia and an oxygen partial pressure of 0.6 psi for a time period of 3hours. Such conditions are hereinafter referred to as “regenerationconditions” to produce a desulfurized nickel-containing sorbent. Thissorbent was then subjected to reducing conditions that included atemperature of 700° F., a total pressure of 15 psia and a hydrogenpartial pressure of 15 psi for a time period of 1.25 hours. Suchconditions are hereinafter referred to as “reducing conditions”.

The resulting solid reduced nickel metal sorbent composition was thenused in Run 2. In this run, hydrogen was added to the cracked-gasolinefeed at a partial pressure of 13.2 psi which resulted in the reductionof sulfur content to less than 5 ppm indicating the sorbent is fullyregenerated and no loss in sulfur removal activity is observed afterregeneration.

A composite of product gasoline from Run 1 was subjected to a test todetermine its Research Octane Number (RON) and Motor Octane Number(MON). The RON and MON for the product from Run 1 were 90.6 and 80.3 ascompared to the RON of 91.1 and MON of 80.0 for the cracked-gasolinefeed, indicating that the octane of the cracked-gasoline wassubstantially unaffected by carrying out the inventive desulfurizationprocess.

The results of this series of runs are set forth in Table 1:

TABLE 1 Run Number Reactor Conditions 1 2 Amount (grams) 10 10 TP¹ 15 15HPP² 13.2 13.2 ° F. 700 700 TOS³ Sulfur⁴ 1 5 5 2 <5 <5 3 5 4 5 5 5 6 5¹Total pressure in psia. ²Hydrogen partial pressure in psi. ³The time onstream in hours. ⁴The amount of sulfur-containing compounds left in thedesulfurized cracked-gasoline in parts per million sulfur by weightbased on the weight of the desulfurized cracked-gasoline.

The specific examples herein disclosed are to be considered as beingprimarily illustrative. Various changes beyond those described will nodoubt occur to those skilled in the art; and such changes are to beunderstood as forming a part of this invention insofar as they fallwithin the spirit and scope of the appended claims.

That which is claimed is:
 1. A process for the production of a sorbentcomposition suitable for the removal of sulfur from a cracked-gasolineor diesel fuel stream which comprises: (a) admixing of zinc oxide,silica and alumina and a calcium compound selected from the groupconsisting of calcium sulfate, calcium aluminate, calcium phosphate andcalcium silicate; (b) particulating the resulting mix so as to formparticles thereof; (c) drying the particulate of step (b); (d) calciningthe dried particulate of step (c); (e) impregnating the resultingcalcined particulate of step (d) with a metal, metal oxide or metaloxide precursor promotor wherein the metal is selected from the groupconsisting of cobalt, nickel, iron, manganese, copper, molybdenum,tungsten, silver, tin and vanadium or mixtures thereof; (f) drying theimpregnated particulate of step (e); (g) calcining the dried particulateof step (f); and thereafter (h) reducing the resulting calcinedparticulate of step (g) with a suitable reducing agent under suitableconditions to produce a particulate composition having a substantialreduced valence promotor metal content therein such that the reducedvalence promotor metal containing composition will effect the removal ofsulfur from a stream of cracked-gasoline or diesel fuel when said streamis contacted with said reduced valence promotor metal containingcomposition under desulfurization conditions.
 2. A process in accordancewith claim 1 wherein said mix is in the form of one of a wet mix, dough,paste or slurry.
 3. A process in accordance with claim 1 wherein saidparticulate are in the form of one of granules, extrudates, tablets,spheres, pellets or mirospheres.
 4. A process in accordance with claim 1wherein said zinc oxide is present in an amount in the range of fromabout 10 to about 90 weight percent, said silica is present in an amountin the range of about 5 to about 85 weight percent, said alumina ispresent in an amount in the range of about 5 to about 30 weight percentand said calcium compound is present in an amount in the range of about5 to about 90 weight percent of the amount of silica present in thesorbent composition.
 5. A process in accordance with claim 4 whereinsaid calcium compound is present in an amount such that the ratio ofsaid calcium compound to said silica is in the range of about 0.1 toabout 0.9.
 6. A process in accordance with claim 1 wherein saidparticulate is dried in steps (c) and (f) at a temperature in the rangeof about 150° F. to about 350° F.
 7. A process in accordance with claim1 wherein said dried particulate is calcined in steps (d) and (g) at atemperature in the range of about 400° F. to about 1500° F.
 8. A processin accordance with claim 1 wherein said zinc oxide is present in anamount of about 39 weight percent, said silica is present in an amountof about 23 weight percent, said alumina is present in an amount ofabout 8 weight percent, said calcium compound is present in an amount ofabout 8 weight percent and the said promotor metal is present in anamount of about 23 weight percent prior to reduction substantially tozero valence.
 9. A process in accordance with claim 8 wherein saidcalcium compound is calcium sulfate and said promotor metal is nickel.10. A process in accordance with claim 1 wherein said reducing agent ishydrogen.
 11. A process in accordance with claim 10 wherein thereduction of said calcined particulate is carried out at a temperaturein the range of about 100° F. to about 1500° F. and at a pressure in therange of about 15 to about 1500 psia for a time sufficient to permit theformation of the reduced valence promotor metal containing composition.